I think my brother and his wife did this. It helped them but I have no idea of the details, including any negatives. They were able to buy a house several years later so it must not have been too bad on the credit score (although when they bought their house the market was a lot different than now). But as far as interest and the like I have no idea. I think they did it when my SIL went on disability and their income dropped unexpectedly.